A solid oxide fuel cell (SOFC) is expected to function as a fuel cell to be installed on a vehicle from viewpoints such as high efficiency and long-time stability. A configuration with the solid oxide fuel cell installed on the vehicle is such that a high voltage battery for motor driving is charged with generated power, and power generation is stopped when the charging is finished. In a solid oxide fuel cell, a protection voltage for protecting an anode electrode is required to be applied from outside to the fuel cell for implementation of stop control (see Japanese Translation of PCT Application Publication No. 2014-523081). In the vehicle, the foregoing high voltage battery or a low voltage battery for driving an auxiliary machine of the vehicle, etc. may be used as a power supply for the protection voltage.